The present invention relates to a machine preparing beverages by mixing a beverage soluble powder and a diluent.
WO 2009/153157 describes a beverage dispensing machine preparing a beverage by dosing a dose of a beverage powder ingredient and delivering the dose in a mixing chamber wherein the powder is mixed with a diluent. The mixing chamber is movable between a first metering position where it is placed under the outlet of the dosing device to receive the powder dose and a second mixing position that is distant from the first position where the diluent is introduced in the mixing chamber and the beverage is prepared and delivered. This machine presents the advantage of avoiding the problem of steam introduction in the dosing device since the diluent is introduced in the mixing chamber when said chamber is not positioned near from the dosing device. WO 2009/144239 describes a dosing device that can be implemented in such a beverage dispensing machine.
This machine usually works efficiently for preparing coffee beverages starting from an instant coffee powder if the coffee powder is not too fine like a freeze-dried instant coffee powder. But when the machine is used with a fine coffee powder like a spray-dried instant coffee powder either agglomerated or micro-agglomerated, it has been observed inconsistency in the dosing and dirtiness in the dosing device. These issues are apparently linked to the presence of instant coffee fines in the mechanism of the dosing device and to the high sensitivity of these fines to steam or vapour around the machine. These issues are intensified if the beverage machine is used in tropical conditions (e.g. with a relative humidity of 70% at 30° C.): the machine can be clogged within a week. Consequently it is not possible to use spray-dried instant coffee with the above machine. Yet it would be an advantage if the machine could be used with any type of instant coffee whatever its properties.
The present invention solves this issue and improves the beverage dispensing machine of the state of the art so that it can be efficiently used with any type of instant coffee and in any climate conditions.